1. Field of the Invention
This invention relates generally to a fastener assembly for use with a power actuated tool which preferably is driven by an explosive charge. The assembly includes a drive pin and a clip member for attaching other articles thereto where the clip provides positive alignment and location of the drive pin with respect to a surface into which the drive pin is driven and provides controlled deformation of the clip during fastening that prevents the clip from failing or being separated from the drive pin when a load is applied to the assembly.
2. Description of the Related Art
Power actuated tools typically drive a fastener into a relatively solid surface, such as structural steel, concrete and the like, by means of some type of explosive powder charge. The fasteners frequently are utilized with various forms of clips from which other articles can be suspended, such as pipes, conduits, ceiling panels or the like.
Such fasteners typically are inserted through an aperture in the clip and are driven into the desired surface by the explosive force provided by the powder charge. During such fastening, the clip frequently is deformed by the fastener which detracts from the strength of the clip causing its premature failure, usually with the fastener remaining attached to the surface.
To restrict clip deformation, the clip can be reinforced about the aperture through which the fastener is driven. An example of such a fastener is illustrated in U.S. Pat. No. 2,961,210 which discloses a fastening assembly including a clip and an annular fastener where the fastener is initially press fitted within an annular hole formed in an annular boss of the clip. As the fastener is driven through the boss, the boss is compressed by the head of the fastener to approximately half its original height and is jammed about the shank of the fastener in an uncontrolled manner. If desired, the side wall of the boss can include slots positioned at selected areas about its periphery to provide one or more pairs of opposing, resilient attaching fingers.
Such a fastener, however, relies on the fastener head and resilience of the material forming the boss to randomly compress the boss without any substantial outward bending or curling of the boss. This type of pure compression causes uncontrolled stress within the clip as well as uncontrolled and unpredictable compression of the boss, either of which can prevent proper fastening and cause failure of the clip when it is subjected to a load. If the boss includes attaching fingers they significantly reduce the ability of the boss to positively guide the fastener in a straight line. If the fastener is tilted or skewed with respect to the surface into which it is being driven it tends to glance off the surface providing a potentially dangerous condition to a user.
It therefore would be desirable to provide a fastener assembly, preferably for use with a power actuated tool, where a drive pin of the fastener is driven through and deforms a clip in a controlled predictable and reproducible manner where the clip provides positive alignment of the drive pin while it is being driven and prevents undesired stress within the clip which could lead to failure and separation of the clip from the drive pin when subjected to a load.